EP1377381B1 - High-gradient magnetic filter and method for the separation of weakly magnetisable particles from fluid media - Google Patents

Abstract

High-gradient magnetic filter and method for the separation of weakly magnetisable particles from fluid media ( 2 ) in a circuit, embodied as a compact, low-maintenance unit with low repair requirements, comprising a housing ( 1 ), for the high gradient magnetic filter, with means for directing the flowing medium ( 2 ) in a pipe system with a feed ( 3 ) and return ( 4 ), a magnetic circuit ( 5 ), forming the high-gradient magnet filter in which at least one filter ( 8 ) is arranged in a filter chamber ( 7 ), formed between the pole faces ( 6 ) of the magnetic circuit ( 5 ), through which the medium ( 2 ) for purification flows, at least one permanent magnet ( 9 ), arranged in the magnetic circuit ( 5 ), for generation of a magnetic field between the pole faces ( 6 ). The magnetic circuit ( 5 ) is separated and sealed off from the flowing medium, the magnetic field between the pole faces ( 6 ) may be alternately switched on and off by means of the permanent magnet ( 9 ), whereupon the discharge and the operation of separating off the particles from the flowing medium may be achieved simply and economically.

Description

Technical area

The invention relates to a high-gradient magnetic filter for separating weakly magnetizable particles from liquid media, whose operation is derived from the physical principle of generating field strength gradients by introducing a ferromagnetic structure into a magnetic field. The invention further relates to a method for operating the high-gradient magnetic filter.

It has prevailed in such filters, to generate the required magnetic field by permanent magnets to produce the units space-saving and cost-effective and to operate more energy efficient compared to the filters with electromagnets.

State of the art

Such a device is already in the DE 33 12 207 A1 described. This contains fixed chambers which are filled with a magnetizable ferromagnetic filling compound. For the supply and discharge of a liquid medium nozzles are provided. Each pair of chambers has a common magnetization arrangement, the magnetic conductor consists of two opposing parts, which on different sides of a are arranged through the middle of these chambers continuous line. Each such part includes a magnet with pole pieces diametrically disposed on the chambers in the direction transverse to the line passing through the centers of the chambers, whereby these two parts, together with the ferromagnetic filter filling masses form a closed magnetic circuit.

The disadvantage here is the still considerable space of the device and the complicated process for the separation of the ferromagnetic materials from the liquid media.

Furthermore, according to the DE 196 26 999 discloses a high gradient magnetic separator having a magnetic unit of two poles which together form a space in which a homogeneous magnetic field can be generated, with a matrix frame which is allowed to rotate about an axis and at least partially an annular one by partitions encloses divided into segments interior space, and at least one inflow and a drain line. The object of this invention is to increase the path of the fluid within the magnetic field. This is achieved in that the width of the magnetic unit along the interior corresponds to at least the width of two segments and in the region of the gap each segment of the annular interior is connected to its adjacent segments via an opening in each case, wherein the openings alternately at a first and a second, the first non-opposite location are attached.

The magnetic field is also built up by permanent magnets, which already allow to make the separator smaller and cheaper and to reduce operating costs.

This device has the disadvantage that the permanent magnets for the required backwashing can not be turned off. The arranged in a carousel filter chambers are therefore cyclically rotated after the filtering process in the magnetic field from the magnetic field area and rinsed in the field-free zone. Subsequently, the filter chambers are rotated back into the magnetic field and again charged with the liquid to be cleaned until the filter is added and a further backwashing must be done outside the magnetic field.

Such a carousel separator requires a structural design that must provide many moving parts and especially numerous seals. This leads to wear and leaks and thus to a considerable maintenance and repair effort, which is e.g. is unacceptable in a municipal sewage plant.

In another high-gradient magnetic separator according to DE-GM 297 23 852.3 at least the sealing problem is resolved. In this case, the individual filter chambers are not moved into and out of the magnetic field. The filter system is fixed and a magnet is mechanically reciprocated to initiate the filtering process or backwashing. However, many moving parts are required here as well.

Finally, a newly developed high-gradient magnetic separator, as found in the WO 01/07167 A1 is disregarded for the problem to be solved because he pursues an altered constructive and separation principle for the separation.

• Die Sieb-/Rostfläche weist quer zu den Magnetsystemen und/oder von einem Magnetsystem zum anderen sich erstreckende Drähte oder Stäbe auf und
• der Eisenquerschnitt ist übersättigt, wobei
• eine gleichmäßige Verteilung der Feldstärke an der Oberfläche des Siebes/Rostes für eine gleichmäßige Abscheidung sorgen soll.

In addition to this relatively new type of high-gradient magnetic separator, so-called older Starkfeld separators are known. Such a Starkfeldscheider is for example the DE 1 177 091 B refer to. This consists of a sieve / grid of magnetically soft iron and connected to the opposite sides of at least two magnet systems, each with unlike poles. In contrast to the current development directions according to the previously analyzed high-gradient magnetic separators, the latter should be characterized as follows:

• The sieve / grate surface has wires or rods extending transversely to the magnet systems and / or from one magnet system to another
• the iron cross-section is supersaturated, with
• a uniform distribution of the field strength at the surface of the screen / grid should ensure a uniform deposition.

• eine hohe Feldkonzentration nicht realisierbar ist,
• die Gefahr einer bleibenden Magnetisierung besteht,
• die zwei Magnetrotoren an den Seiten eine kompakte Bauweise verhindern,
• die Reinigung bestenfalls durch zusätzliche und aufwändige z. B. Brauseeinrichtungen erfolgen soll und
• ein im eigentlichen Sinne ein konsruktiv und technologisch zu integrierendes Spülsystem noch gar nicht angesprochen ist.

Alone, this design and characterization does not allow use as a high-gradient magnetic separator, because

• a high field concentration is not feasible,
• the danger of permanent magnetization exists,
• the two magnet rotors on the sides prevent a compact design,
• the cleaning at best by additional and elaborate z. B. shower facilities and should
• a flushing system that is in the true sense a brewing and technologically to be integrated is not even addressed.

• eine Übersättigung des Eisenquerschnitts ,
• der geschlossene Magnetkreis,
• die unvorteilhafte Verteilung des magnetischen Feldes

ein effizientes Abtrennen der Teilchen, so auch das Abtrennen von schwach magnetisierbaren Partikeln aus dem Medium, nicht erreichbar macht.It follows for the skilled person with regard to the development direction to be taken that the disadvantages resulting from this prior art, such as

• a supersaturation of the iron cross section,
• the closed magnetic circuit,
• the unfavorable distribution of the magnetic field

an efficient separation of the particles, as well as the separation of weakly magnetizable particles from the medium, makes unreachable.

Presentation of the invention

The invention has for its object to provide a high-gradient magnetic filter for separating weakly magnetizable particles from liquid media, which - using a permanent magnet for generating the magnetic field - is a compact, maintenance and low-repair assembly, the process of separation of the particles simply designed and the permanent magnet for the required backwashing makes ineffective. The variety of parts or number should be further reduced and the sealing problem eliminated. The method according to the invention for operating the high-gradient magnetic filter is intended to ensure efficient use thereof.

• ein den Hochgradienten-Magnetfilter aufnehmendes Gehäuse mit Mitteln zur Führung des flüssigen Mediums in einem Rohrsystem mit Vorlauf und Rücklauf,
• einen den eigentlichen Hochgradienten-Magnetfilter bildenden Eisenkreis, in dem sich in einer, zwischen Polschuhen des Eisenkreises ausgebildeten Filterkammer ein Filter befindet, das von dem zu reinigenden Medium durchströmt wird,
• mindestens einen in dem Eisenkreis angeordneten Permanentmagneten zur Erzeugung des Magnetfeldes zwischen den Polschuhen, wobei dieser Teil des Eisenkreises zu dem flüssigen Medium getrennt und somit abgedichtet ist, und
• das Magnetfeld zwischen den Polschuhen, welches mittels des Permanentmagneten abschaltbar und wieder einschaltbar ist,

wobei erfindungsgemäß ein Rohrsystem zum umgekehrt gerichteten Spülen des Filters (8) bei abgeschaltetem Magnetfeld vorgesehen ist.According to claim 1, this is achieved in that the high-gradient magnetic filter comprises according to the task

• a high-gradient magnetic filter receiving housing with means for guiding the liquid medium in a piping system with flow and return,
• an iron circuit forming the actual high-gradient magnetic filter, in which a filter is located in a filter chamber formed between pole shoes of the iron circuit and through which the medium to be cleaned flows;
• at least one arranged in the iron circle permanent magnet for generating the magnetic field between the pole pieces, said part of the iron circuit is separated and thus sealed to the liquid medium, and
• the magnetic field between the pole shoes, which can be switched off and switched on again by means of the permanent magnet,

wherein according to the invention a pipe system for reversely directed purging of the filter (8) is provided with the magnetic field switched off.

With the features of claims 2 to 5, the inventive concept is further developed.

The invention can be realized functionally in two variants according to claims 6 to 8 or 9.

The one variant provides to form the permanent magnet as a rotor and rotatably arranged in the correspondingly shaped part of the iron circle. The angle of rotation of the rotor is adjustable so that the field strength between the pole pieces from a minimum to a maximum field strength value can be selected in order to adjust the field strength of the different materials of the particles to be separated. It is also possible to adjust the angular position of the rotor, e.g. 90 ° or in other angular steps to lock.

The other variant of the invention is to form the permanent magnet as a linearly displaceable piece in the correspondingly shaped part of the iron circle.

For these variants of the invention, the expedient embodiments of the features of claims 10 to 20 can be seen.

1. a) Beaufschlagung des Filters mit dem zu separierenden Medium über das Rohrsystem mit Vorlauf und Rücklauf bei eingeschaltetem Magnetfeld im Eisenkreis zwischen den Polschuhen und Durchsetzung des Magnetfeldes in der vom Medium durchspülten Filterkammer am Filter, wobei sich infolge der hohen Feldgradienten am Filter die magnetisierbaren Partikel anlagern und dabei die Feldstärke entsprechend der Winkelstellung des Permanentmagneten unterschiedlich stark einstellbar ist, danach
2. b) Abschalten des Magnetfeldes des Permanentmagneten
   realisiert wird, wonach erfindungsgemäß
3. c) die Entfernung der angelagerten und separierten Partikel vom Filter in einem Spülvorgang als Gegenstromverfahren oder auch als Gleichstromverfahren erfolgt und
4. d) eine Wiederholung der Schrittfolge a), b) und c) bis zur Beendigung der Abtrennung der Partikel aus dem flüssigen Medium abläuft.

The inventive method for operating the high gradient magnetic filter according to the steps of claims 21 or 22 is carried out so that the separation of the weakly magnetizable particles from the liquid medium mutually in the pipe system according to the task according to the steps

1. a) loading the filter with the medium to be separated via the pipe system with flow and return with the magnetic field in the iron circuit between the pole pieces and enforcement of the magnetic field in the purged by the medium filter chamber on the filter, which accumulate due to the high field gradients on the filter, the magnetizable particles and while the field strength is set to different degrees according to the angular position of the permanent magnet, thereafter
2. b) switching off the magnetic field of the permanent magnet
   is realized, according to the invention
3. c) the removal of the accumulated and separated particles from the filter in a flushing process as a countercurrent process or as a DC process and takes place
4. d) a repetition of the sequence of steps a), b) and c) until completion of the separation of the particles from the liquid medium takes place.

The method is according to the features of claims 23 or 24 with respect to the medium or the media differently ausgestaltungsfähig.

Furthermore, the method according to claim 25 can be operated efficiently by the use of a program for controlling the clocks of the advancing and returning medium or flushing medium in operative connection with the magnetic field to be switched on and off and the magnetic field strength to be set, the program also performing the functions according to FIGS Features of claims 26 to 28 includes.

The invention will be explained with reference to exemplary embodiments.

Brief description of the drawings

Fig. 1

den erfindungsgemäßen Hochgradienten-Magnetfilter in vereinfachter Darstellung im durch den Rotor 10 eingeschalteten Zustand,

Fig. 2

den Hochgradienten-Magnetfilter nach Fig. 1 im ausgeschalteten Zustand,

Fig. 3

die Erfindungsvariante mit schematischer Darstellung des Permanentmagneten 9 als linear verschiebbares Stück 11,

Fig.4

die schematische Darstellung des Rotors 10 mit dem Permanentmagneten 9 aus Einzelpermanentmagneten 12,

Fig. 5

die schematische Darstellung des Rotors 10 mit Antrieb 13,

Fig. 6

das Prinzip der Lagerung des Rotors 10 und

Fig. 7

das Prinzip einer erfindungsgemäßen Doppelausführung mit zwei Filtern 8 und einem Rotor 10.

In the drawings show

Fig. 1

the high-gradient magnetic filter according to the invention in a simplified representation in the state switched on by the rotor 10,

Fig. 2

the high-gradient magnetic filter of Figure 1 in the off state,

Fig. 3

the variant of the invention with a schematic representation of the permanent magnet 9 as a linearly displaceable piece 11,

Figure 4

the schematic representation of the rotor 10 with the permanent magnet 9 of Einzelpermanentmagneten 12,

Fig. 5

the schematic representation of the rotor 10 with drive 13,

Fig. 6

the principle of storage of the rotor 10 and

Fig. 7

the principle of a double embodiment according to the invention with two filters 8 and a rotor 10th

Best way to carry out the invention

1 and 2, the high-gradient magnetic filter according to the invention consists in its essential structure of a housing 1, in which a pipe system for guiding a liquid medium 2 (arrows), are separated from the weakly magnetizable particles, with a flow 3 and a Return 4 is provided. For this purpose unillustrated means are used, e.g. belonging to the general state of the art valve control blocks that control the respective flow 3 and return 4 of the medium 2 in a mutual circulation.

Within the housing 1 there is an iron circle 5, in which a filter 8, which is flowed through by the medium 2, is located in a filter chamber 7 formed between pole shoes 6 of the iron circle 5. In the iron circuit, a permanent magnet 9 is arranged, which generates a magnetic field between the pole pieces 6 in the state shown in FIG. 1 and thus passes through the filter 8.

The entire part of the iron circuit 5 is always separated from the liquid medium 2 and thus sealed, wherein the pipe system with the flow 3 and return 4 is space-saving enclosed by the iron circuit 5.

In FIGS. 1 and 2, the variant of the invention is shown with a permanent magnet 9 designed as a rotor 10. The rotor 10 is equipped with Einzelpermanentmagneten 12 of FIG. 4. Fig. 5 shows the schematic representation of a drive 13 for the rotor 10, with which this shuts off the magnetic field (Figure 2) and turns on (Figure 1). Conveniently, the rotor 10 is provided with an axle 14 slidably and rotatably received in bearings 15 (Figure 6).

The variant of the invention with the permanent magnet 9 as a linearly displaceable piece 11, which z. B. sliding and via a drive, not shown, the magnetic field on and off again, is shown schematically in Fig. 3, wherein the design of this high-gradient magnetic filter may result in analogy to FIGS. 1 and 2.

According to this constructive basic structure, in which the pipe system according to the invention is provided for reversely purging the filter (8) with the magnetic field switched off, advantageous embodiments are possible, which are realized depending on the intended use and efficiency and can be represented as follows:

Depending on the nature of the separated, weakly magnetizable particles from the liquid media 2, the angle of rotation of the rotor 10 can be adjusted so that the acting field strength between the pole pieces 6 from a minimum to a maximum field strength value is selectable. This makes it possible to largely adapt the field strength acting on the different materials of the particles, and the separation effect can be influenced. If it is expedient, the rotor 10 can also be rotated 90 ° or in other angular steps and locked.

In order to increase the throughput and efficiency of high-gradient magnetic filter according to the invention and to reduce the specific construction cost, the embodiment according to FIG. 7 is proposed in which the iron circuit 5 is designed such that two filters 8 are provided, which are simultaneously provided by a permanent magnet 9 are each acted upon or turned off with a magnetic field in the on state. Fig. 7 shows the permanent magnet 9 as a rotor 10, wherein throughput and efficiency can be increased by the linearly displaceable piece 11 as a permanent magnet 9, if this corresponds to a correspondingly designed or arranged iron circle 5 and at least two filters 8, each with a magnetic field provided.

1. 1. In der ersten Schrittfolge wird mindestens ein Filter 8 mit dem zu separierenden flüssigen Medium 2 über das Rohrsystem beaufschlagt. Das Rohrsystem ist in einem Vorlauf 3 und einem Rücklauf 4 wechselseitig anwendbar, wobei in dieser ersten Schrittfolge bei eingeschaltetem Magnetfeld im Eisenkreis 5 zwischen den Polschuhen 6 z. B. gemäß Fig. 1 der Vorlauf 3 und der Rücklauf 4 des flüssigen und zu reinigenden Mediums 2 dargestellt sind. Dabei durchsetzt das Magnetfeld den vom Medium 2 mittels des Rohrsystems durchspülten Filter 8, welches z.B. aus einem magnetisierbaren Drahtgewebe besteht. Infolge der hohen Feldgradienten am Filter 8 lagern sich die magnetisierbaren Partikel im Drahtgewebe an. Die Feldstärke kann entsprechend der Drehung (Rotor 10) oder Verschiebung (linear verschiebbares Stück 11) des Permanetmagneten 9 unterschiedlich stark eingestellt werden.
2. 2. Danach wird in der weiteren Schrittfolge das Magnetfeld des Permanentmagneten 9 (Rotor 10 / linear verschiebbares Stück 11) abgeschaltet. Das oder ein Medium 2 mit einem nun umgekehrt gerichteten Vorlauf 3 und Rücklauf 4 (z.B. entsprechend der Fig. 2) entfernt die am Drahtgewebe des Filters 8 angelagerten und separierten Partikel in einem Spülvorgang. Diese Spülung ist in mehreren Variationen durchführbar, indem z.B.
   • ein zu reinigendes und von den Partikeln zu befreiendes Medium 2 als Spülmedium oder
   • ein separates Medium 2 als Spülmedium
   durch entsprechende Führung im Rohrsystem mittels Ventilsteuerung im Vorlauf 3 und Rücklauf 4 verwendet werden.
3. 3. Wiederholung dieser vorbeschriebenen Schrittfolgen im ständigen wechselseitigen Umlauf, wobei das Filter 8 je nach Zustand oder Verbrauch aus der Filterkammer 7 herausnehmbar oder austauschbar ist, um es z. B. zu ersetzen.

The process principle according to the invention for operating all conceivable design variants according to the invention covered in claims 1 to 20 provides that the separation of the weakly magnetizable particles from the liquid medium 2 alternately takes place in the pipe system according to the following steps according to claims 21 to 24:

1. 1. In the first step sequence, at least one filter 8 is acted upon by the liquid medium 2 to be separated via the pipe system. The pipe system is in one Flow 3 and a return 4 mutually applicable, in this first step sequence when the magnetic field in the iron circuit 5 between the pole pieces 6 z. B. of FIG. 1, the flow 3 and the return 4 of the liquid and to be cleaned medium 2 are shown. In this case, the magnetic field passes through the flushed by the medium 2 by means of the pipe system filter 8, which consists for example of a magnetizable wire mesh. As a result of the high field gradients on the filter 8, the magnetizable particles deposit in the wire mesh. The field strength can be set to different degrees according to the rotation (rotor 10) or displacement (linearly displaceable piece 11) of the permanent magnet 9.
2. 2. Thereafter, in the further step sequence, the magnetic field of the permanent magnet 9 (rotor 10 / linearly displaceable piece 11) is turned off. The or a medium 2 with a now reversely directed flow 3 and return 4 (eg, corresponding to FIG. 2) removes the deposited on the wire cloth of the filter 8 and separated particles in a rinsing process. This conditioner is feasible in several variations, eg
   • a to be cleaned and freed from the particles medium 2 as a flushing medium or
   • a separate medium 2 as flushing medium
   be used by appropriate guidance in the pipe system by means of valve control in the flow 3 and return 4.
3. 3. Repetition of these above-described sequences of steps in the constant mutual circulation, wherein the filter 8 is removable or replaceable depending on the state or consumption of the filter chamber 7 to make it z. B. to replace.

Both variations are structurally executable in Gegenstrom- (claim 21 b)) or in the DC method (claim 22).

With a program according to claim 25, the cycles of the advancing and returning medium 2 or flushing medium can be controlled in the mutual circulation in operative connection with the magnetic field to be switched on and off and the magnetic field strength to be set for all design and process variants.

The method is tunable with the features described in claims 26 to 28 both complex and variable for different applications.

Industrial Applicability

• einerseits eine kompakte, wartungs- sowie reparaturarme Baueinheit mit für die Wartung vorteilhaft austauschbaren Baugruppen geschaffen wird und
• andererseits der Ablauf und der Betrieb der Abtrennung der Partikel aus flüssigen Medien einfach sowie kostengünstig durchgeführt werden können, wobei
• schließlich die beschriebenen Nachteile des Standes der Technik beseitigt sind und eine vielfältige Anwendung in verschiedenen einschlägigen Industrien möglich wird.

The construction and process principle according to the invention is characterized in its industrial application by the fact that

• on the one hand, a compact, low-maintenance and low-repair assembly with advantageously exchangeable for maintenance assemblies is provided and
• On the other hand, the course and operation of the separation of the particles from liquid media can be carried out simply and inexpensively, wherein
• Finally, the disadvantages of the prior art described are eliminated and a variety of applications in various relevant industries is possible.

LIST OF REFERENCE NUMBERS

1 =

casing

2 =

Liquid medium

3 =

leader

4 =

returns

5 =

iron circuit

6 =

pole

7 =

filter chamber

8 =

filter

9 =

permanent magnet

10 =

rotor

11 =

linearly displaceable piece

12 =

Einzelperrnanentmagnet

13 =

drive

14 =

axis

15 =

camp

N =

North Pole

S =

South Pole

Claims (28)

1. A high-gradient magnetic filter for separating weakly magnetisable particles of liquid media (2) in a circulation, comprising

   - a housing (1) with means for guiding the liquid medium (2) in a pipe system with feed (3) and return (4),

   - an iron circuit (5), accommodated in the housing (1), in which circuit is located at least one (filter) in a filter chamber (7) formed between pole shoes (6) of the iron circuit (5), through which filter flows the medium (2) to be cleaned, and

   - at least one permanent magnet (9) arranged in the iron circuit (5) for generating a magnetic field between the pole shoes (6), wherein the iron circuit (5) is separate and therefore sealed from the liquid medium (2),

   wherein the magnetic field between the pole shoes (6) can be switched off and on again alternately by means of the permanent magnet (9),
   characterised by a pipe system for washing the filter (8) in the opposite direction when the magnetic field is switched off.
2. The high-gradient magnetic filter according to Claim 1, characterised by

   a) device for feeding the medium (2) acted upon on both sides throughout the length of the filter (8), and

   b) a closed pipe system (3, 4) which is enclosed by the iron circuit (5).
3. The high-gradient magnetic filter 1 or 2, characterised in that the length of the filter (8) is ≤ the length of the pole shoe (6).
4. The high-gradient magnetic filter according to one of Claims 1 to 3, characterised in that the cross-sections of the connections of the filters (8) for the medium (2) are designed so that the filter is subjected to uniform flow of the medium (2) and the filter chamber (7) is suitably designed for this.
5. The high-gradient magnetic filter according to one of Claims 1 to 4, characterised in that the housing (1) is designed as a frame for receiving a component for the pole system (5, 6) and for receiving a component for the pipe system (3, 4).
6. The high-gradient magnetic filter according to one of Claims 1 to 5, characterised in that the permanent magnetic (9) is designed as a rotor (10) and is rotatably arranged in the suitably designed part of the iron circuit (5).
7. The high-gradient magnetic filter according to Claim 6, characterised in that the angle of rotation of the rotor (10) can be set from a minimum to a maximum field strength value.
8. The high-gradient magnetic filter according to Claim 6 or 7, characterised in that the angle of rotation of the rotor (10) can be set to 90°.
9. The high-gradient magnetic filter according to Claim 1 to 5, characterised in that the permanent magnet (9) is designed as a linearly displaceable piece (11) in the suitably designed part of the iron circuit (5).
10. The high-gradient magnetic filter according to one of Claims 1 to 9, characterised by such a design of the iron circuit (5) that at least two filters (8) are provided which are switched on or off by a permanent magnet (9) simultaneously or alternately in respect of each magnetic field that can be acted upon.
11. The high-gradient magnetic filter according to one of Claims 1 to 10, characterised in that the permanent magnet (9) consists of a plurality of individual permanent magnets (12).
12. The high-gradient magnetic filter according to one of Claims 1 to 11, characterised in that the permanent magnet (9) is connected to a drive (13).
13. The high-gradient magnetic filter according to Claim 6, characterised in that the rotor (10) is mounted with its shaft (14) in bearings (15).
14. The high-gradient magnetic filter according to Claim 9, characterised in that the linearly displaceable piece (11) is mounted in bearings.
15. The high-gradient magnetic filter according to one of Claims 1 to 14, characterised in that the filter (8) consists of magnetisable wire fabric or magnetisable steel wool.
16. The high-gradient magnetic filter according to one of Claims 1 to 14, characterised in that the filter (8) represents a cage with magnetisable material, such as wire fabric, steel wool or chips, enclosed therein.
17. The high-gradient magnetic filter according to Claim 15, characterised in that the filter (8) can be removed from the filter chamber (7) or replaced.
18. The high-gradient magnetic filter according to one of Claims 15 to 17, characterised in that the internal arrangement of the filter (8) is designed in such a manner, for optimising the separation, that the medium (2) flowing through it passes through the filter (8) in an alternating direction of flow.
19. The high-gradient magnetic filter according to one of Claims 15 to 18, characterised in that

    a) means are provided in the filter (8) which guarantee the flow of the medium (2) at right angles or transversely to the entire surface of the magnetisable wire fabric, the magnetisable steel wool or chips, and

    b) the longitudinal axes of the individual components, such as wires of the wire fabric or steel wool, and of the chips, do not run in the direction of the magnetic field.
20. The high-gradient magnetic filter according to one of Claims 15 to 19, characterised in that the filter (8) consists of a plurality of individual filters (8).
21. A method for operating a high-gradient magnetic filter according to Claim 1, wherein the separation of the weakly magnetisable particles from the liquid medium takes place alternately in the pipe system according to the following steps:

    a) loading of at least one filter (8) with the liquid medium (2) to be separated via the pipe system in a feed (3) and a return (4) when the magnetic field is switched on in the iron circuit (5) between the pole shoes (6) and dispersion of the magnetic field in the filter chamber (7) of the filter (8) through which the medium (2) flushes, wherein the magnetisable particles are taken up due to the high field gradient on the filter (8), and wherein the field strength can be set to different values according to the rotation or displacement of the permanent magnet (9), then

    b) switching off of the magnetic field of the permanent magnet (9)
    characterised by

    c) removal of the particles taken up and separated from the filter (8) in a flushing process as a counterflow with feed (3) and return (4) in the opposite direction, and

    d) repetition of step sequence a), b) and c) until the end of separation of the particles from the liquid medium (2).
22. The method according to Claim 21, characterised in that the flushing process takes place in the direct current, wherein the step sequence is determined by

    - the flushing medium (2) feed

    - the contaminated flushing medium (2) return.
23. The method according to Claim 21 or 22, characterised by the use of the medium (2) to be cleaned and to be released from the particles as flushing medium.
24. The method according to Claim 21 or 22, characterised by the use of a separate medium (2) as flushing medium.
25. The method according to Claims 13 to 15, characterised by the use of a programme for controlling the cycle of the feeding and returning medium (2) or flushing medium in actuating connection with the magnetic field to be switched on and off and the magnetic field strength to be set.
26. The method according to one of Claims 21 to 25, characterised in that before the absorption capacity of the filter (8) is reached it is switched off.
27. The method according to one of Claims 21 to 26, characterised in that if a plurality of filters (8) is used, at least one is switched for accumulation of the particles and at least another is switched for the flushing process.
28. The method according to one of Claims 21 to 27, characterised in that the control of the cycles is switched as a function of a time and/or a differential pressure.

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